CVE-2025-40004

linux: In the Linux kernel, the following vulnerability has been resolved: net/9p: Fix buffer overflow in USB transport lay...

CVE-2025-40004 is fixed in linux on 1 platform, first by DEBIAN-CVE-2025-40004, released October 20, 2025. It is not reported as exploited. Patch Radar priority: Routine.

Routine
CVSS
n/a
No vendor severity
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0027
18th percentile

In the Linux kernel, the following vulnerability has been resolved: net/9p: Fix buffer overflow in USB transport layer A buffer overflow vulnerability exists in the USB 9pfs transport layer where inconsistent size validation between packet header parsing and actual data copying allows a malicious USB host to overflow heap buffers. The issue occurs because: - usb9pfs_rx_header() validates only the declared size in packet header - usb9pfs_rx_complete() uses req->actual (actual received bytes) for memcpy This allows an attacker to craft packets with small declared size (bypassing validation) but large actual payload (triggering overflow in memcpy). Add validation in usb9pfs_rx_complete() to ensure req->actual does not exceed the buffer capacity before copying data.

Where it's fixed

ProductFixed inFixReleased
Linux
linux · Debian 13.5 (trixie) 6.12.57-1 DEBIAN-CVE-2025-40004 Oct 20, 2025
linux · Debian 14 6.17.6-1 DEBIAN-CVE-2025-40004 Oct 20, 2025

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